Fast pyrolysis apparatus and method

ABSTRACT

A fast pyrolizer includes an elongated tubular housing having a feed inlet to receive material, an outlet, and a flow path. The flow path has an internal contact surface extending from the inlet to the outlet. The inlet is to be oriented to a non-vertical relative elevation with respect to the outlet. At least a portion of the internal contact surface directly contacts the material. A heater heats the internal contact surface such that the material is heated via direct thermal transfer from the internal contact surface.

TECHNICAL FIELD

The disclosure herein relates to fast pyrolysis of material.

BACKGROUND

Pyrolysis is a thermal decomposition of organic material at high temperatures in the absence of oxygen. In order to achieve maximum yields of liquid (or bio-oil chemical species) from the pyrolysis of materials, fast pyrolysis is the usual method utilized. Fast pyrolysis is usually defined by the heating rate and residence time of the material and the time of flight of the evolved gases. The heating rate for fast pyrolysis is usually in the range of 100 deg. C./s to 10,000 deg. C./s. The material being pyrolized usually stays in the reactor for a duration of 0.5 to 5 seconds. The resulting gas containing the decomposed chemicals is rapidly removed and either quenched or cooled (<2 s). Also, very little to no oxygen is usually present in the pyrolysis reactor to avoid oxidation reactions which would reduce the liquid yields of bio-oil species.

Various fast pyrolysis reactors have been proposed, including those having fluidized beds, moving augers, or free-falling tubes. While these various schemes may work well for their particular applications, the respective heat transfer capabilities and operational complexities render the systems somewhat undesirable for industrial applications

What is needed is a more economical and practical system and method to quickly pyrolize material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one example of a system that employs fast pyrolysis for extracting bio-oil components from pyrolyzed material.

FIG. 2 illustrates one embodiment of a fast pyrolizer that may be used in the system of FIG. 1.

FIGS. 3A-3H illustrate various specific embodiments of an elongated tubular housing capable of being used by the fast pyrolizer of FIG. 2.

FIG. 4 illustrates a close-up view of section 5-5 of the fast pyrolizer of FIG. 2 that employs an elevator according to one embodiment.

FIG. 5 illustrates a close-up view of section 4-4 of the fast pyrolizer of FIG. 2 that employs a heater according to one embodiment.

FIG. 6 illustrates a flow chart for one embodiment of a method of fast pyrolysis.

DETAILED DESCRIPTION

Examples of apparatus, methods and systems are described below that provide for fast pyrolysis of material. In one embodiment, a fast pyrolizer includes an elongated tubular housing having a feed inlet to receive material, an outlet, and a flow path. The flow path has an internal contact surface extending from the inlet to the outlet. An elevator is coupled to the housing to orient the inlet to a non-vertical relative elevation with respect to the outlet. At least a portion of the internal contact surface is to directly contact the material. A heater heats the internal contact surface such that the material is heated via direct thermal transfer from the internal contact surface.

Examples further provide for a method of pyrolizing material including providing a fast pyrolizer that has an elongated tubular housing. The housing includes a feed inlet, an outlet, and an internal contact surface extending from the inlet to the outlet. The inlet has a relative elevation with respect to the outlet. Heat is transferred to at least the internal contact surface. Material is fed into the inlet where contact between the material and the heated internal contact surface pyrolizes the material.

Yet additional examples provide for a system that includes a fast pyrolizer to pyrolize material. A condenser is coupled to the fast pyrolizer to receive the pyrolized material and condense pyrolized gas into a liquid. An oil extractor extracts bio-oil from the condensed liquid. The fast pyrolizer includes an elongated tubular housing having a feed inlet to receive material, an outlet, and a flow path. The flow path has an internal contact surface extending from the inlet to the outlet. The inlet is oriented to a non-vertical relative elevation with respect to the outlet. At least a portion of the internal contact surface directly contacts the material. A heater heats the internal contact surface such that the material is heated via direct thermal transfer from the internal contact surface.

System Description

Although illustrative embodiments are described in detail herein with reference to the accompanying drawings, variations to specific embodiments and details are encompassed by this disclosure. It is intended that the scope of embodiments described herein be defined by claims and their equivalents. Furthermore, it is contemplated that a particular feature described, either individually or as part of an embodiment, can be combined with other individually described features, or parts of other embodiments.

FIG. 1 illustrates a system, generally designated 100, that employs fast pyrolysis in an application for extracting bio-oil components. It is but one example of an application for fast pyrolysis. The system 100 includes a pyrolizer 102 where material is exposed to heat with little or no oxygen present. The pyrolized material is then fed to a condenser 104 where, for example, bio oil may be condensed from the gases generated by the pyrolizer. An oil extractor 106 may then extract the condensed bio oil for use as a fuel. The material fed to the pyrolizer 102 may contain petroleum compounds, plastics, tires, biomass (both vegetal and animal), solid wastes, extracts of liquid wastes, or a combination thereof, and the like. The material is usually solid, but can also be or contain liquids.

One specific embodiment of a pyrolysis reactor, or pyrolizer, generally designated 200, is shown in FIG. 2. The pyrolizer includes an elongated hollow tube or reactor 202 formed of metal with a feed inlet 204 and an outlet 206. To minimize complexity, the interior of the tube forms an unobstructed flow path, and includes no moving parts. The flow path includes at least one interior surface 208 that forms a contact surface for material progressing through the tube.

The elongated hollow tube, or reactor 202, may be formed from different alloys of stainless steel to avoid oxidation. However, a proper selection will often depend on the mechanical, electrical and magnetic properties of the metal. Carbon steel can also be used. Although the corrosion resistance of carbon steel is much less than that of stainless steel, considering that the inside of the reactor is usually not exposed to oxygen, and also its price, electrical properties and magnetic properties, standard carbon steel may be very attractive to use for an economical reactor. The magnetic properties are important depending on the selection of the heat generation device, as is explained below. Aluminum and aluminum alloys can also be used as building materials for the reactor. Any metal cladding can also be used for improved passivation to the harsh conditions the reactor can be subjected to. Electro-deposition, anodizing are also other methods to passivate the metal on its surface to avoid oxidation or reduction of the ramp reactor. These coating techniques can be very attractive to keep the costs low while still using the core material's characteristics.

Various alternative embodiments for the shape of the elongated reactor 202 are shown in FIGS. 3A-3H. The reactor could basically have any cross-sectional shape, but those offering the best material-surface contact are those with a flat bottom. This optimizes the conduction mode of heating. Moreover, the opposite wall of the contact surface must also not be placed too far from the material falling through it, in order to take advantage of radiation heating. Square, rectangular, or half-circle reactors are preferable. However, other cross-section configurations could also be used, like triangular or trapezoidal. It is also possible to transit to other cross-sectional shapes and thicknesses along the tube length.

In its most straightforward form, the reactor is a straight tubular element from the feed inlet to the outlet, and shown in FIG. 3A, at 302. In this case, and if the coefficient of friction is neglected (since the material is degassing rapidly), the material entering the tube will have a constant acceleration. In other words, the speed of the material sliding through the reactor will constantly increase, until it exits the outlet.

FIG. 3B illustrates an alternative tube construction that maintains the rectangular cross section, but curves the tube, at 304. This results in the flowing material decreasing its acceleration, but at a constant speed. FIG. 3C illustrates an embodiment where the tube curves laterally back and forth (zigzagged), at 306, to increase path and residence time, and also to increase the mixing of the material falling through the flow path. To further mix the material as it flows through the tube, plural fixed transverse mixing elements 308 may be employed throughout the length of the tube, as shown in FIG. 3D.

For many applications, a straight elongated hollow tube works well for its straightforward nature and robustness during operation. However, in some situations, space is limited. FIGS. 3E-3G illustrate tube constructions that employ a coiled configuration to minimize space, yet maximize surface area contact for pyrolysis. It is possible to twist the tube while maintaining the optimum free-sliding angle for the material to flow through to be optimally thermally treated. The general material properties will help determine the slopes (elevation angle of tube) for optimum spread and speed for thermal treatment.

FIG. 3E shows a high coil tube, at 310. For this configuration, gravity is still the main drive force to move the material through the length of the tube. In FIG. 3F, at 312, a more compact form of the coiled tube is shown that cannot rely on gravity alone to move the material. For such a construction, a mechanical device such as a vibration mechanism or pressure device may be employed to cooperate with gravity in moving the material through the flow path.

For relatively long residence times, the tube may be relatively flat, such as that shown in FIG. 3G, at 314. For even longer residence times, it is possible to force the substance to be treated upwards the reactor ramp. In such case, when a vibration device is attached to the reactor, a mesh or rough reactor floor will help prevent the substance from flowing back downward to the inlet. Moreover, such a compact coiled reactor can alternatively use an open top, or U-shaped ramp, to rapidly remove the gases generated during thermal treatment. In this case, an outer shell surrounding the whole coil may be used. However, the radiative mode of heat transfer can still be used but only when the coil is with a very low profile. The heat from the coil floor above will serve to heat the material by radiation. Alternatively, an enclosed coil could also have a series of holes along its side walls to rapidly remove the gases in the same manner as the topless ramp. In this later design detail, as shown in FIG. 3H, an outer shell 316 may be utilized to contain the gases.

Other variations in the reactor shape are possible. Because the organic particles lose weight and volume during their thermal treatment, in regards to the optimization of the conduction mode of heat transfer as well as optimization of the heating source, it is possible that the reactor width could be reduced along the path of the material falling through. Furthermore, the width reduction would also reduce the overall weight and cost of the reactor. The reactor ramp may also be constructed of separate longitudinal elements joined together, instead of one large tube. In some cases, the joining mechanism is preferred to be non-electrically conductive, with a non-electrically conductive joint.

Referring back to FIG. 2, the elongated hollow tube is oriented such that the feed inlet 204 is elevated relative to the outlet 206. Where the relative elevation is at or greater than a critical free-sliding angle, the force of gravity directs the material downwardly through the tube. In some situations, the relative elevation angle may be less than the critical free-sliding angle. In such circumstances, an additional driving force such as the vibration or pressure device noted above may be used to assist gravity in drawing the material through the tube. Generally speaking, the critical free-sliding angle depends on the characteristics of the material, its density, its weight, particle size, etc. Injection of high velocity oxygen-less gas would help move the organic material through the reactor but would also disturb the material bed and most likely lift if from the bottom, thus breaking the heat conduction efficiency. For this reason, a mechanical means, such as through vibration, to move the material along the reactor is preferred.

Further referring to FIG. 2, and in particular section 4-4 (shown close-up in FIG. 4), the angle of the reactor can be fixed for a given process but the system can also incorporate mechanical elements permitting for the reactor angle to be changed for optimization of the process. To allow for adjusting the elevation angle, a pivot 402 may be employed for raising and lowering the tube. While FIG. 4 shows a half-pivot, which enables for easy removal of the ramp, various other shapes may also be employed. A support (not shown) at the other end of the tube keeps the feed inlet at the desired height.

FIG. 5 illustrates a close-up view of section 5-5 of FIG. 2, and shows one specific embodiment of a heater 502 that employs strip heater elements 504 that are held against the periphery of the reactor by a removable clip 506. Instead of a removable clip, permanent mounting materials may be used to secure the heater elements to the tube. As seen in FIG. 2, multiple heaters are distributed along the length of the reactor to optimize the heating. Heating rods, strips, or other types of Joule or infrared heaters can be attached or be part of the reactor faces. As a minimum, only the contact (bottom) face should be heated. With proper insulation the other faces could reach a temperature sufficient enough to help the fast heating process. Ultimately, all faces should be heated in this fashion for optimal heat transfer to the substance flowing through the reactor. Another advantage of such system is the possibility of heating different zones to different temperatures.

As alternatives to the strip heaters described above, various other heating methods could be used to heat the reactor. For example, gas burners are maybe the most well developed methods for heating processes. However, their efficiencies are not as good as some other methods. The efficiency can be improved when integrated with other processes from a pyrolysis plant, like using syngas from pyrolysis. In order to use gas burners with the present ramp reactor, it will be important to use a shell on the ramp to contain the combustion gases, such as that shown in FIG. 3H. A layer of high efficiency thermal insulator significantly reduces heat loss. The burners can be installed inside the outer shell of the ramp or produced separately in a burner box. The hot combustion gases can then be directed inside the ramp reactor outer shell to heat the ramp uniformly.

Heat transfer fluid (i.e. air, combustion gases, syngas, thermal oil, ionic or liquid salts, fluidized solid particulates, etc.) can be heated remotely using gas burners or via electrical heating and subsequently transferred to a shell built around the reactor where the heat will be transferred to all faces of the reactor. The fluid may be returned to the heating box to be reheated or discarded appropriately.

The reactor ramp could also be heated directly using the Joule heating effect by an electrical current passing through it. In this case, the ramp should be completely isolated electrically from all other equipment attached to it, including sensors. When the ramp includes more than one electrically insulated section, it is possible to heat each section independently to different temperatures.

Induction heating can also be used to heat the reactor. A single induction coil can be placed around a straight reactor. It is also possible to use multiple coils. The multiple coils can be controlled individually by one or more induction generators. A single induction generator can also be used in a switching mode using an internal or external switcher to alternatively turn on and off each coil. In this manner, a smaller induction generator can be used to heat a very long section of reactor. Two spiral induction coils can also be used to heat a spiral reactor. A series of spiral reactors can be heated by a series of spiral coils. As is often the case, standard water cooled induction coils must be thermally insulated from the heated ramp as not to cool down the ramp reactor. However, it is also possible to use wire coils, but in this case there would be advantages to include the heat generated by the current going through the wires by installing them in close physical proximity to the ramp element, inside the insulation layer.

In the case of induction heating, a ferro-magnetic construction material for the ramp also offers an added advantage of adding magnetic and electrical hysteresis effects to the standard Eddie current induction heating, increasing the overall induction effect which results in a more efficient heating of the ramp reactor. Moreover, in the case of pyrolysis of material, given a high enough induction current, it is also possible to turn the charred layer on the material being pyrolyzed into a heating device. It is known that graphite like material can heat up when submitted to an electrical induction field. Induction heating can also be used to generate heat directly in the bulk of the material particles being pyrolyzed, always in close proximity to the unpyrolyzed material, inducing a very high heating rate, but also high liquid yields. This latest phenomenon can also be extended to other applications, including catalysis, cracking, etc.

The rate of heating is important for complete thermal treatment within the time of flight inside the reactor, as well as obtaining maximum liquid yield. Although a single method for heating the reactor ramp could be used, it could be advantageous to use different heating devices to heat different zones along the path of the ramp reactor. The following is simply one example but many cross features can be used consistent with this idea. A thin section for the first section could be used along with induction heating to have a very rapid heat transfer/generation as fresh and relatively cold material comes in through the ramp reactor entrance, the ramp could then transition to a thicker construction material and be heated using electrical heating strips. The heat generation/transfer in that reactor zone does not need rapid response but a sustained temperature since the material was already preheated in the first zone. These changes in thickness and heating zones can help maximize the thermal treatment efficiencies while reducing equipment and operation costs.

The fast thermal treatment apparatus described herein can be used for many different applications, including thermal treatment of solids, liquids and gases. It can be used for drying or evaporation. It can be used as a fast chemical reactor. It can also be used for fast pyrolysis and gasification. It can also be used in many different applications where a control of the atmosphere is necessary.

Method Description

FIG. 6 illustrates high-level steps for a method of pyrolizing a material. Reference is made to the embodiment of FIG. 2 in describing elements of FIG. 6.

At 602, a fast pyrolysis reactor is provided that includes an feed inlet, an outlet, and internal walls. The reactor inlet is oriented to a non-vertical elevation with respect to the outlet for gravity feed flow, at 604. A user may then feed material into the reactor inlet, at 606. As the material progresses through the reactor, it is heated via direct heat transfer between the material and at least one of the internal walls, at 608. The resulting pyrolized material and gases may then be further processed, depending on the application, at 610.

Those skilled in the art will appreciate the benefits and advantages afforded by the embodiments disclosed herein. By providing a re-circulator to recycle a bio-oil component solvent mixture in a condensing process as well as extracting and recycling the solvent, significant logistical and cost savings may be realized in the extraction of bio-oil components in a pyrolysis system. Further, by controlling the temperature of the solvent based on a desired end-temperature, an optimal extraction during condensation may be attained.

It is contemplated for examples described herein to extend to individual elements and concepts described herein, independently of other concepts, ideas or system, as well as for examples to include combinations of elements recited anywhere in this application. Although examples are described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise examples. As such, many modifications and variations will be apparent to practitioners skilled in this art. Accordingly, it is intended that the scope of the invention be defined by the following claims and their equivalents. Furthermore, it is contemplated that a particular feature described either individually or as part of an example can be combined with other individually described features, or parts of other examples, even if the other features and examples make no mentioned of the particular feature. Thus, the absence of describing combinations should not preclude the inventor from claiming rights to such combinations. 

1. A fast pyrolizer, comprising: an elongated tubular housing having a feed inlet to receive material, an outlet, and a flow path with an internal contact surface extending from the inlet to the outlet, the inlet to be oriented to a non-vertical relative elevation with respect to the outlet to allow a flow of the material via gravity and/or vibration, at least a portion of the internal contact surface to directly contact the material; and a heater to generate heat for the internal contact surface such that the material is heated via direct thermal transfer from the internal contact surface such that pyrolysis occurs in the flow path.
 2. (canceled)
 3. The fast pyrolizer according to claim 1, wherein the raised non-vertical elevation corresponds to a critical free-sliding angle.
 4. The fast pyrolizer according to claim 1, wherein the raised non-vertical elevation corresponds to an angle that is less than a critical free-sliding angle, and wherein the pyrolizer further includes a material driver to cooperate with gravity to direct the material through the tubular housing.
 5. The fast pyrolizer according to claim 4, wherein the material driver comprises a pressure source to pressurize the inlet with respect to the outlet.
 6. The fast pyrolizer according to claim 1, wherein the inlet is to be oriented to a lowered relative elevation with respect to the outlet, and wherein the pyrolizer further includes a vibrator disposed outside of the flow path.
 7. The fast pyrolizer according to claim 1, wherein at least a portion of the tubular housing includes a rectangular cross-section.
 8. The fast pyrolizer according to claim 7, wherein a first portion of the tubular housing includes a rectangular cross-section, and a second portion of the tubular housing includes a non-rectangular cross-section.
 9. The fast pyrolizer according to claim 1, wherein the tubular housing is straight.
 10. The fast pyrolizer according to claim 1, wherein the tubular housing further includes plural internal elements disposed transverse to the flow path and connecting oppositely disposed internal walls of the housing.
 11. The fast pyrolizer according to claim 1, wherein the tubular housing takes the form of one from the group comprising: a zig-zagged shape, a curved shape, or a spiral shape.
 12. The fast pyrolizer according to claim 1, wherein the heater comprises at least one heater element surrounding a cross-sectional portion of the tubular housing.
 13. The fast pyrolizer according to claim 12, wherein plural heater elements are distributed along the length of the elongated tubular housing.
 14. The fast pyrolizer according to claim 1, and further comprising: an elevator coupled to the housing to orient the inlet to the non-vertical relative elevation with respect to the outlet.
 15. The fast pyrolizer according to claim 14, wherein the elevator includes a pivot disposed proximate the outlet, and a support to maintain the feed inlet at a non-vertical angle with respect to the outlet.
 16. A method of pyrolizing material, the method comprising: providing a fast pyrolizer, the fast pyrolizer including an elongated tubular housing with a feed inlet, an outlet, and an internal contact surface extending from the inlet to the outlet; elevating the inlet with respect to the outlet sufficient to allow gravity flow of the material through the housing; transferring heat to at least the internal contact surface; and feeding the material into the inlet where contact between the material and the heated internal contact surface pyrolizes the material.
 17. The method of claim 16, wherein the elevating includes: elevating the inlet sufficient to allow gravity flow of the material through the housing.
 18. The method of claim 17, wherein the elevating includes: elevating to a critical flow-through angle.
 19. The method of claim 17, wherein the elevating includes: elevating to a non-critical flow-through angle; and assisting gravity to drive the material through the housing without internal moving parts.
 20. The method of claim 19, wherein assisting gravity comprises: vibrating the housing.
 21. The method of claim 19, wherein assisting gravity comprises: pressurizing the inlet with respect to the outlet.
 22. The method according to claim 16, wherein elevating includes lowering the inlet with respect to the outlet, and the method further comprises: vibrating the housing to drive the material through the housing.
 23. A system comprising: a fast pyrolizer to pyrolize material; a condenser coupled to the fast pyrolizer to receive the pyrolized material and condense pyrolized gas into a liquid; an oil extractor to extract bio-oil from the condensed liquid; and wherein the fast pyrolizer includes an elongated tubular housing having a feed inlet to receive material, an outlet, and a flow path with an internal contact surface extending from the inlet to the outlet, the feed inlet oriented to a non-vertical relative elevation with respect to the outlet to allow a flow of the material via gravity and/or vibration, at least a portion of the internal contact surface to directly contact the material; and a heater to heat the internal contact surface such that the material is heated via direct thermal transfer from the internal contact surface such that pyrolysis occurs in the flow path.
 24. The system of claim 23, further comprising an elevator to raise the feed inlet to a relative elevation with respect to the outlet.
 25. (canceled)
 26. The system of claim 23, wherein the relative elevation comprises lowering the inlet with respect to the outlet, and the system further comprises a vibrator disposed external to the flow path to drive the material through the housing. 